1. Field
The present invention relates to an electromagnetic relay, and in particular, to a drive mechanism of a gate-shaped iron core and movable iron piece.
2. Related Art
There is an electromagnetic relay that includes a nearly C-shaped, plate-shaped yoke having a horizontally extending body and legs extending downward from both ends of the body; an insulating winding frame having a winding body attached to the body and an excitation coil wound around the winding body; an armature having a horizontal part horizontally extending and having an insulating operating piece, a pivoting shaft extending from one end of the horizontal part in the extending direction of one leg out of the legs, and a vertical part extending from the other end of the horizontal part and coming into contact with the other leg out of the legs when the excitation coil is excited; an insulating base housing supporting the both legs of the yoke and having a recess or a hole receiving a shaft piece formed at the lower end of the pivoting shaft of the armature, the base housing having an insulating wall extending between the excitation coil and the armature; and a movable contacting piece and a fixed contacting piece that are arranged below the excitation coil and between the both legs of the yoke to be attached to the base housing and come into contact with each other by the pressing of the operating piece, the base housing having a second insulating wall isolating the movable and fixed contacting pieces and the armature from each other, and the operating piece pressing the movable contacting piece through a hole formed at nearly the central part of the second insulating wall (refer to Patent Literature 1).
As illustrated in its FIG. 2, in the above electromagnetic relay, a pivoting shaft 62 of an armature 60 is in contact with the surface of one leg 42 of a plate-shaped yoke 40, and the armature 60 pivots about a rectangular shaft piece 62a and a rectangular shaft piece 62b formed on the same axis. This causes a protrusion 65 of an operating piece 64 to drive a movable contacting piece 21 and causes a movable contact 21d to connect to and disconnect from a fixed contact 22d. 
In particular, the above electromagnetic relay arranges the protrusion 65 at a position downwardly deviated from the central position between the rectangular shaft piece 62a and the rectangular shaft piece 62b. When a voltage is applied to an excitation coil 56 of an operating electromagnet 30, the pivoting shaft 62 of the armature 60 pivots while remaining to be attracted to the one leg 42 of the plate-shaped yoke 40. When the protrusion 65 of the operating piece 64 comes into contact with an elastic spring piece 21c, a torsional moment about a line connecting between the rectangular shaft piece 62a and the protrusion 65 acts on the armature 60. Because a larger pivot angle of the armature 60 increases the torsional moment, the rectangular shaft piece 62a of the armature 60 departs from the one leg 42, and the tip edge of a vertical part 63 is attracted to the other leg 43 of the plate-shaped yoke 40.
This causes the armature 60 to be supported by three points, that is, the rectangular shaft piece 62b above the armature 60, the protrusion 65 of the operating piece 64, and the tip edge of the vertical part 63 of the armature 60, thereby achieving a stable state.